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[InstCombine] Create zero constants on demand.

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No functional change intended.

llvm-svn: 235257
This commit is contained in:
Benjamin Kramer 2015-04-18 16:52:08 +00:00
parent fa43478f01
commit 18e9411446
1 changed files with 2 additions and 4 deletions
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6
lib/Transforms/InstCombine/InstCombineCasts.cpp
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@ -1770,19 +1770,17 @@ Instruction *InstCombiner::visitBitCast(BitCastInst &CI) {
// If the source and destination are pointers, and this cast is equivalent
// to a getelementptr X, 0, 0, 0... turn it into the appropriate gep.
// This can enhance SROA and other transforms that want type-safe pointers.
Constant *ZeroUInt =
Constant::getNullValue(Type::getInt32Ty(CI.getContext()));
unsigned NumZeros = 0;
while (SrcElTy != DstElTy &&
isa<CompositeType>(SrcElTy) && !SrcElTy->isPointerTy() &&
SrcElTy->getNumContainedTypes() /* not "{}" */) {
SrcElTy = cast<CompositeType>(SrcElTy)->getTypeAtIndex(ZeroUInt);
SrcElTy = cast<CompositeType>(SrcElTy)->getTypeAtIndex(0U);
++NumZeros;
}
// If we found a path from the src to dest, create the getelementptr now.
if (SrcElTy == DstElTy) {
SmallVector<Value*, 8> Idxs(NumZeros+1, ZeroUInt);
SmallVector<Value *, 8> Idxs(NumZeros + 1, Builder->getInt32(0));
return GetElementPtrInst::CreateInBounds(Src, Idxs);
}
}